The present invention relates to a conveying device for transporting material goods with at least one profiled rail, with at least one transported goods support that is supported by the at least one profiled rail and is moveable along this rail, and with a drivable conveyor means extending along the at least one profile rail, whereby the at least one transported goods support has at least one engagement unit, which is in locked-in engagement with the conveyor means or which can be brought into locked-in engagement with the conveyor means.
These types of transfer systems serve in a production line for transporting work pieces between individual stations, for example, at which machining or assembly processes take place. By way of example, reference is made to the catalogue “Transfersystem TS2” of Robert Bosch GmbH. In addition to the connection of manual working stations, these transfer systems are suited also for use with an automated assembly, based on their high positioning accuracy.
With this known system, the transported goods support lies loosely on two continuously circulating conveyor means, for example, belts or chains, which receive the work pieces (see catalogue, page 1-1). The work pieces are machined on the transported goods support. At the machining and assembly stations, the transported goods support is individually stopped or slowed, while the conveyor means runs further with unchanged speed. This has the result that between the transported goods support and the conveyor means, a relative movement occurs. Depending on which conveyor means is used and how heavy the transported goods support and work pieces are, on the basis of the friction between the conveyed goods support and the conveyor means, a more or less intense wear occurs on the transported goods support and conveyor means. The known system requires a high-powered drive, since this must serve not only for driving the transported goods support in the area of the conveyor section of the production line, but also for overcoming the static friction between the conveyor means and the transported goods support in the area of the machining and assembly stations coming from the weight of the work pieces and transported goods support.
The latter problem of the coupling of weight and driving force is resolved with the known conveying device of DE 198 25 955 A1. With this conveying device, the transported goods supports are longitudinally, movably supported via castors on a slide rail. With a first embodiment, the slide rail has a drive band guide, in which a friction band is guided. A frictional surface of the transported good support stands in force-locking, locked-in engagement with this friction band. With a holdup of the transported goods support, the friction-locked engagement of the transported goods support with the friction band is interrupted. Based on the relative movement between the friction band and the transported goods support, wear occurs on the contacted surfaces.
With a second embodiment of DE 198 25 955 A1, a driving change with finger-like engagement pieces is used, which engages the transported goods support form-lockingly. The engagement fingers are can be folded away, in order to make possible stopping of the transported goods support. In addition to the expense design of the driving chain with the foldable engagement pieces, wear and abrasion of the drive device still occurs also with this embodiment with stopping of the transported goods support, based on the impact of the engagement fingers against the transported goods support.
Finally, DE 198 25 955 A1 discloses a third embodiment, which represents a combination of the first two embodiments, and so, likewise, has the same disadvantages, in particular, the disadvantage of wear of the drive device which cannot be ignored.
For the sake of completeness, reference is made to DE 195 17 276 A1, DE 32 12 224 A1, and DE-PS 1 192 103 as further examples of the state of the art.
In conclusion, the primary disadvantage of the state of the art is that with a slowing or stopping of the transported goods support for enabling machining of the work pieces arranged thereon, wear and abrasion of the drive means, for example, the drive band, which is important for the ordinary functioning of the drive device, occurs.
In contrast, it is an object of the present invention to provide a conveying device of the above-described type, which displays a minimal, or negligible, wear of the conveyor means.
This object is solved according to the present invention, in which the engagement unit has an engagement element revolving about a bearing unit and in which, in addition, a coupling assembly, in particular, in inhibitive coupling assembly, is provided, which affects the revolving movement of the engagement element. In this manner, wear upon stopping or slowing of the transported goods support cannot occur on the functional surfaces of the transported goods support and conveyor means responsible for the locked-in engagement, rather on the coupling assembly specially provided for this purpose and indeed, then, when this includes a frictional assembly. This frictional assembly can be optimized in its function as a friction coupling, in particular by its construction and the selection of the material used. When the coupling assembly has a magnetic coupling, then the revolving movement of the engagement element can be affected also nearly wear-free.
In both embodiments, frictional coupling or magnetic coupling, an adjustment assembly can be provided, by means of which the amount of the affect of the revolving movement of the engagement element can be changed. In the case of the friction assembly, the adjustment assembly can affect the pressing force of the frictional assembly against the revolving engagement element. The adjustment arrangement can change the width of an air gap in the case of a magnetic coupling, which separates the two magnetically interactive magnetic coupling parts from one another. In addition, the adjustment assembly can serve for an integrated abrasion adjustment. In both embodiments, the adjustment arrangement can act on the coupling assembly for an effective use of the structural space available in an operating direction running substantially orthogonally to a revolving plane of the engagement element.
It is also contemplated that the revolving engagement element is formed as a revolving band or chain. Preferably, however, a wheel is used as the revolving engagement element, since its bearing is constructively simpler and its engagement with the conveyor means is more rigid and effective, based on its substantially rigid structure, compared with a band or chain. It is also advantageous if the engagement element and the conveyor means are in a positive-fit, locked-in engagement. Essentially, also a frictional engagement between the engagement means and the conveyor means is contemplated. This requires, however, a precise determination of the friction forces between the engagement element and the conveyor means on the one hand, as well as the engagement element and the coupling assembly on the other hand, in order to guarantee that upon stopping or slowing of the transported goods support, the required relative movement also occurs between the engagement element and the coupling assembly. Particularly preferred, then, is if the conveyor means is formed as a toothed belt and the engagement element is correspondingly formed as a cogwheel.
In order to ensure a regular engagement of the engagement element and the conveyor means, it is proposed that at least one profile rail has a guide section, which is guidingly engaged with the bearing element. Moreover, the guide section acts on the bearing element resiliently, in order to maintain the engagement between the bearing element and the conveyor means. Thus, the forces occurring between the conveyor means and the engagement element upon stopping or slowing of the transported goods support can be at least partially reduced by this resiliency. This favorably affects the abrasion of the engagement element and the conveyor means.
For a regular engagement of the engagement element and the conveyor means, it is also advantageous if at least one profile rail has a guide recess for guiding the conveyor means.
In a further form of the invention, it is provided that at least one profile rail has a sliding section, on which the at least one transported goods support lies. This gliding section can thereby include a separately formed sliding strip, which, for example, is held in a groove, preferably in a positive fit. Alternatively, however, it is also possible that the sliding section is a sliding shoulder formed as one-piece on the profile rail. In each case, the gliding strip or the gliding section can be made from a low-friction material, so that the frictional force to be overcome that comes from the force of weight upon conveying the transported goods support along the profile rail and from the drive device only has a minimal value.
The same advantage also can be achieved if at least one profile raise has a guideway for at least one linear slide associated with the transported good support, whereby, for example, a castor guide or a rotating ball guide or a ball castor assembly can be used.
For reducing the susceptibility to failure of the drive device, in a further embodiment of the invention, it is proposed that at least one profile rail has a resetting channel for the conveyor means. A resetting channel can be eliminated, if also the returning section of the conveyor means runs past stations or is used for driving of the transported goods support.
It can be advantageous, too, not only for the simple structure of this resetting channel, if at least one profile rail is formed as a multiple pieces with at least one support profile and at least one guide profile. In this connection, the support profile can be formed as a light metal profile, preferably, an aluminum profile, and the guide profile can be formed as a plastic profile. The two profiles, for example, can connect to one another by locking on of the plastic profile onto the light metal profile. The guide profile formed from plastic, therefore, can have the previously mentioned guide recesses for the conveyor means and the guide section for the bearing element. The resilient pressing of the bearing element against the conveyor means by means of the guide section can be accomplished, for example, by an inherent elasticity of the plastic material of the guide section. Basically, however, also the use of a one-piece profile rail is contemplated.
In order to enable slowing or acceleration of the movement of the transported goods support, it is proposed that the engagement element can be brought into engagement with an auxiliary engagement assembly at least along a part of the conveying track near the conveyor means. In this connection, the auxiliary engagement assembly can be formed fixedly in the simplest design, for example, as a gear rod. Such a fixed, auxiliary engagement assembly leads to a constant changing of the speed of the transported goods support for a time period predetermined by its extension in the movement direction of the transported goods support. Alternatively, the auxiliary engagement assembly also can be formed as a revolving or rotating engagement assembly, for example, as a toothed belt with a separate drive. With a revolving, auxiliary engagement assembly, the movement of the transported goods support can be accelerated and/or decelerated in any desired manner. Thus, also a reversal of the movement direction of the transported goods support is contemplated.
The conveying device of the present invention, then, also can be used as a table-type transported goods support, which lies on two profile rails, which is driven by means of a drive device, and whose conveyor means is merely provided on these profile rails. This is particularly advantageous because in this manner, a change of the width of the transported goods support need not cause a width change of the drive device. In addition, curve sections and branches from the confluence in the main track can be realized without expensive additional units, such as, for example, roller curves, lift-transverse units, and the like.
When each transported goods support has at least two engagement elements, then the discharging and feeding of a transported goods support from or into the main extension can be realized in a simple manner, in particular, without use of additional drives, since the drive device of the main track and secondary track can be arranged, such that at each point in time, always at least one of the engagement element is engaged with the conveyor means of the main track or the secondary track.